APPLICATION OF A MULTI-DIMENSIONAL WATER TRANSPORT MODEL TO REPRODUCE THE TEMPORAL CHANGE OF RUNOFF AMOUNT

Japan, a warm-snow re-gion, by combining the numerical snowpack model, SNOWPACK, and a multi-dimensional water transport model. The SNOWPACK simulation was first performed in order to obtain the layer structure, snow density, grain size, and water content of the snow. Secondly, changes due to rain and snowmelt were extracted from the output of SNOWPACK. For each event, water transport simulations were per-formed using the water transport model. Within the water transport simulation, the initial snow parameters and the amount of snowmelt were taken from the output results of SNOWPACK. The multi-dimensional simulation showed different characteristics from the one-dimensional simulation, as the liquid water infil-trated the dry snow layer. Simulated time series of runoff amounts was compared with the lysimeter data. Although using the multi-dimensional simulation, as opposed to the single-dimensional simulation, miti-gated the delay of the simulated runoff, it proved insufficient because of the effect of preferential flow. The results suggest that it is necessary to consider the densification of snow and the formation of snow dim-ples.